2004 Pontiac Grand Am - sensor, combustion, and misfire codes

My car have been idling hard, hard to climb a hill and hesitate at the stop light. The guy at Advance Auto hooked the diagnostic tester and said it showed sensors, mis-fires and combustion. What could the problem be? I was told my engine, transmission and spark plugs.

Guy at Advance is not a mechanic. He is a parts seller.

Post those codes here so can help you. The numbers not the descriptions… P1234 type codes.

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YOu haven’t provided enough information. Could be caused by any of 50 different problems. So yea, it could be the engine, transmission, and/or spark plugs; but knowing that isn’t going to do you much good. As posted above, for more help here you’ll have to provide the actual powertrain diagnostic codes.

Absent the codes, hard to climb a hill might be a clogged catalytic converter. Rough idling and hesitation at stop light might be a faulty vacuum system.